Cellular systems, such as LTE systems, use licensed spectrum. Operators may acquire, e.g. by government auction, the right to utilize a certain part of a frequency band in a certain geographical area for transmission and reception of cellular signals. An operator may have exclusive use of licensed spectrum to provide services to its users without concern for in-band interference by other communication systems. In contrast, unlicensed spectrum remains unclaimed and may be used for a variety of purposes by a variety of users employing a variety of radio access technologies (RATs).